Compositions of matter comprising halogenated organic compounds



9 1951 A. M. ELLENBURG 5 9 COMPOSITIONS OF MATTER COMPRISING HALOGENATED ORGANIC COMPOUNDS. Filed Aug. 10, 1949 FIG.2

CHLORINATED BIPHENYL, TRICHLORBENZENE AND A THIENYL TIN COMPOUND WI (4444 4444 444 WWW/ 4444 DIELECTRIC CONTAINING ELECTRODES HG 1 HALOGENATED ORGANIC COMPOUND AND A THIENYL TIN COMPOUND FIG 4 #1111111mum/1111111111L FIG-.5

METAL FOIL PAPER IMPREGNATED WITH HALOGE NATED ORGANIC COMPOUND AND A THIENYL TIN ARTHUR M. ELLENBURG FIG 3 COMPOUND INVENTOR.

BY l mEEG? M ATTORNEY Patented Nov. 6, 1951 COMPOSITIONS OF MATTER COMPRISING HALOGENATED ORGANIC COMPOUNDS Arthur M. Ellenburg, Anniston, Ala., assignor to Monsanto Chemical Company, St. Louis, Mo., a

corporation of Delaware Application August 10, 1949, Serial No. 109,576

16 Claims. 1

The present invention relates to novel compositions of matter comprising halogenated organic compounds and a thienyl tin compound as a scavenging or corrosion inhibiting material. More specifically, the invention relates to apparatus, particularly electrical apparatus such as capacitors, transformers, circuit breakers, cables and the like containing the above compositions.

Halogenated organic compounds, more particularly halogenated aromatic compounds such as chlorinated biphenyl and chlorinated naphthalene are highly useful electrical insulating materials because of their high dielectric constants, thermal stability, resistance to oxidation, non-flammability and other valuable properties. However, it has been found that when exposed to elevated temperatures and/or high voltages, they partially decompose liberating hydrogen halides which have an exceedingly deleterious action on the paper insulation and metal parts of electrical apparatus.

For example, in transformers, circuit breakers and other electrical devices in which arcing occurs, the development of hydrogen halides as a result of the above decomposition presents a serious problem as they decrease the dielectric strength of the composition containing same and cause considerable damage by attacking paper insulation and corroding metal parts of the apparatus in which the composition is used. The undesirable effect of the above decomposition is further manifested when the above halogenated organic compounds are used as capacitor impregnants. Thus, under high operating temperatures and direct current voltages, capacitors impregnated therewith undergo a characteristic type of deterioration which results in an ever increasing leakage current, a short capacitor life, visible localized decomposition of the dielectric and corrosion of the electrodes. Moreover, in the case of capacitors operating on alternating current, the decomposition sometimes results in an excessive increase in power factor of the dielectric material.

It is, therefore, the object of the present invention to provide new compositions of matter containing halogenated organic compounds wherein the above objectionable properties are either completely eliminated or substantially reduced. I

An additional object is to provide transformers, capacitors, circuit breakers, cables and the like containing halogenated organic compounds in combination with a corrosion inhibitor or scavenger whereby the deleterious action of hydrogen halides on the paper insulation and metal parts thereof is eliminated or materially reduced.

Another object is to provide a capacitor impregnant containing halogenated organic compounds and a corrosion inhibitor or scavenger, whereby the deleterious effect of hydrogen halides on the electrodes and paper insulation of capacitors is substantially reduced or completely eliminated with the result that the capacitor has a longer useful life and greater dielectric stability than similar capacitors not containing the corrosion inhibitor.

A further object is to provide the cellulosic insulation in transformers containing liquid halogenated organic compounds with protection against rapid destruction by hydrogen halides evolved as the result of a minor are within the transformer, thus permitting complete repair of the assembly by rapid replacement or removal of the particular part that gave rise to the arc and thereby avoiding destruction of the entire paper insulation of the transformer with a consequent high cost of repair.

A still further object is to provide switches, cables and the like containing halogenated organic compounds and a corrosion inhibitor or scavenger which practically eliminates the rusting and corrosion normally accompanying the use of such devices filled with halogenated on ganic compounds per se.

Other objects and advantages of the present invention will become apparent to those skilled in the art as the description proceeds.

I have discovered that halogen decomposition products can be rendered substantially innocuous and the above objectives accomplished if, in accordance with the present invention, the halogenated organic materials to be protected are associated with a relatively small amount of one or more of the group of compounds defined by the following general formula Ro-11.Sn (041 11.

inwhich R represents an organic radical, at least one of which is a thienyl group, 2; corresponds to 3 the valence of tin and n is selected from the group of values consisting of 1 and 2 when 1) is 2 and l, 2 3 and 4 when '0 is 4. Where R represents organic groups other than the thienyl radical, it is understood that aliphatic, alicyclic and aryl hydrocarbon groups are contemplated. Specific examples of thienyl tin compounds defined by the above general formula are tetra-a-thienyl tin, tetra-,B-thienyl tin, di-a-thienyl tin, di-p-thienyl tin, triphenyla-thienyl tin, triphenyl-c-thienyl tin, diphenyl di-a-thienyl tin, diphenyl di-fi-thienyl tin, dibutyl di-e-thienyl tin, dibutyl di-fl-thienyl tin, phenyl tri-a-thienyl tin, phenyl tri-p-thienyl tin, butyl tri-a-thienyl tin, butyl tri-p-thienyl tin, tributyl-a-thienyl tin and tributyl fi thienyl tin. Of these compounds, tetra-a-thienyl tin is preferred as it exhibits outstanding properties from the standpoint of inhibiting the deleterious action of halogen decomposition products on metal and organic insulation materials.

For a more complete understanding of; the present invention, reference is made to the accompanying drawings and. the experimental data hereinafter presented in the specific examples.

Figure l is a front elevation partly in section of a transformer; Figure 2 illustrates a switch in a similar manner; Figure 3 represents a rolled capacitor; Figure 4 shows a sectional view of a portion of the electrodes and dielectric sheets of Figure 3; and Figure 5 is a side view of a cable, the casing being partly removed to permit the interior of the parts to be seen.

The transformer illustrated in Figure 1 comprises a casing 3, core 2, coils 3 insulatedwith manila paper, kraft paper, cotton or other fibrous insulation, insulating and cooling medium 2, leadin bushings 5, and suitable leads 5 connected to the coil assembly. The insulating and cooling medium may consist of chlorinated biphenyl, trichlorbenzene and tetra-athienyl tin in the following proportions.

Parts by weight Chlorinated biphenyl (60% Cl)--. 60 Trichlorbenzene 40 'Ietra-e-thienyl tin or another thienyl tin compound lg. M--. -s 0.1

Other well known liquid halogenated hydro= carbons or mixtures thereof may be used as the insulating and cooling liquid and various other halogenated organic compounds may constitute a part of such compositions, such as for example, halogenated compounds of naphthalene, toluene, benzene, nitrodiphenyl, diphenyl oxide, diphenyl ketone, diphenyl methane, diphenyl ethane, terphenyls, quaterphenyls, etc.

The presence of 0.05 to 0.1 part by weight of tetra-a-thienyl tin in the cooling and insulatin liquid will not only substantially reduce the deleterious eii'ect of such liquid on organic insulation but will also greatly reduce the corrosion of the metal parts of the transformer which come in contact therewith in the presence, vor absence of air.

The switch shown in Figure 2 comprises a casing 5, fixed contacts l and 8, and movable con tacts 9 and lil which cooperate therewith. The movable contacts are mounted upon a support I l which in turn is operatively connected to actuatinglevers i2. The following is illustrative of a 4 in this device, it being understood that the invention is not limited thereto.

Parts by weight Chlorinated biphenyl (55% Cl) Trichlorbenzene 20 Di-a-thienyl tin or another thienyl tin compound 0.05

In the operation of electric switches, the unavoidable arcing which accompanies make-andbreak of the switch contacts results in partial decomposition of the chlorinated biphenyl or other halogenated organic compounds. The presence of di-a-thienyl tin in the above liquid renders the halogen decomposition products innocuous with the result that switches provided therewith are substantially free from the corrosion normally accompanyin the use or" such devices filled with halogenated organic compounds per se.

The capacitor shown in Figure 3 is made up of alternate layers of metal foil such as aluminum or tin foil separated by sheets of dielectric material. It is produced by interleaving two dielectric sheets, such as linen or kraft paper, with the metal foil, and rolling the interleaved sheets in the conventional manner. The rolled capacitor is then impregnated with the dielectric composition by any suitable process, such as vacuum impregnation with chlorinated biphenyl having dissolved therein a small proportion of a thienyl tin compound. The capacitor is then placed in a protective case or otherwise used as desired.

The following range of compositions is illustrative of suitable capacitor impregnants:

Composition I Per cent by weight Liquid chlorinated biphenyl, particularly chlorinated biphenyl containing-from-42% to 60% by weight of chlorine Conventionai chlorinated organic dielectric materials About Triphenyl-a-thienyl tin 0.01-1

Composition II Parts by weight Chlorinatedbiphenyl (42%60% Cl)- 75 Trichlorbenzene n- 25 Triphenyl-e-thienyl tin 0.1

Of the above range of compositions, the preferred capacitor impregnant is one having the following composition:

Parts by weight Chlorinatedbiphenyl (55% Cl) g '75 Trichlorbenzene. l 25 flfriphenyl-e-thienyl tin 0.1

suitable ar quenching liquid Whichmay be; used 75 capacitors impregnated with halogenated organic materials which are not associated with one of the above corrosion inhibitors.

Figure 4 shows a section of one turn of the finished rolled capacitor illustrating the alternate electrodes and dielectric layers. In accordance with the present invention, the finished capacitor contains a halogenated organic compound, preferably chlorinated biphenyl, and a minor proportion of a thienyl tin compound such as triphenyl-a-thienyl tin.

The cable of Figure 5 comprises a core 13, cable conductors I l, insulation consisting of paper or other suitable material I5 and a casing IS. The space between the insulated conductors and the casing is filled with a mixture of a thienyl tin compound and any of the liquid chlorinated organic compounds mentioned above. Such a composition may consist of a mixture of the following ingredients, but it is to be clearly understood that the invention is not restricted thereto.

Parts by weight Chlorinated biphenyl (60% Cl) 50 Trichlorbenzene 50 Tetra-a-thienyl tin About 0.1

The experimental data hereinafter presented illustrate in a striking manner the scavenging or corrosion inhibiting action of di-a-thienyl tin and tetra-a-thienyl tin on dielectric compositions containing halogenated organic compounds. In accordance therewith, the effect of the corrosion inhibitor is brought out by showing and comparing the action of an HCl-saturated halogenated dielectric composition, with and without the inhibitor, on organic dielectric materials such as pa per. The effectiveness of the inhibitor is manifested by the protection it affords paper against attack by hydrogen chloride and the degree of attack is indicated by the extent to which the tensile strength of the paper is decreased. This will be rendered more apparent by reference to the following examples.

Example I Six strips of manila wrapping paper (6" x l) were humidified at 65% R. H. at 70 F. for a period of 48 hours and subjected to tensile strength tests. These tests were run on a Scott IP-2 serigraph with a jaw separation of 3 inches and a rate rated solution consisting of parts by weight of chlorinated biphenyl (60% Cl) and 40 parts by weight of trichlorbenzene and at the end of this operation, the papers were soaked for 15 minutes in benzene, another 15 minutes in methanol and dried. After cutting one half inch from each end of the dried paper strips, they were subjected to the above tensile strength tests with the following result:

Tensile strength of impregnated paper samples 11.5 lbs/in.

These examples demonstrate that HCl had a highly deleterious action on the samples since the tensile strength of the paper changed from 46.2 lbs/in. to 11.5 lbs./in., a decrease in tensile strength of approximately Examp e III The foregoing example was repeated using samples of the same paper and the same impregnant except that 0.1 part by weight of tetraa-thienyl tin was added. The tensile strength of the impregnated paper was found to be 36 lbs./in., thus demonstrating that the above compound isa highly efiective material for rendering halogen decomposition products such as HCl innocuous to paper or other fibrous organic dielectrics.

Example IV The procedure described in Example III was followed except that di-a-thienyl tin in an amount corresponding to 0.1 part by weight was substituted for tetra-a-thienyl tin. The paper samples had an average tensile strength of 21 lbs./ in. as compared with 11.5 lbs./ in. for the samples treated with impregnant not containing a scavenger, and 46.2 lbs. /in. for the unimpregnated samples.

This example shows that di-a-thienyl tin is less effective than tetra-a-thienyl tin; however, it is still a highly satisfactory scavenger or corrosion inhibitor for halogenated organic com pounds as it is superior to tetraphenyl tin, a material used commercially for the above purpose.

The following table illustrates the electrical properties of the dielectric composition consisting of 60 parts by weight of chlorinated biphenyl (60% Cl) and 40 parts by weight of trichlorbenzene and also shows the effect thereon of adding 0.1 part by weight of tetra-a-thienyl tin and diof travel of 34.5 seconds for a load of 40 lbs. The a-thienyl tin respectively.

Volume D1electr1c Dielectric Strength, Constant, g%g$ 0.1in. Gap, 1 kc., D C obe Chlorinated biphenyl 60 parts by wt Kv.

60 C1) 3. 8 100 1o Trichlorbenzene "40 parts by wt Ghlogiflrgtgdfiphenyl 60 parts by wt Trichlor benzene 40 parts by wt 46 0 7740x109 Tetra-a-thienyl tin O.l part by wt Chlogi)i 1 /at&d)biphenyl 60 parts by wt Trichlo benzene 40 parts by wt 52 0 SOXIOB Di-a-thienyl tin 0.1 part by wt result of these tests, being the average of 6 breaks, was as follows:

Tensile strength of paper samples 46.2 lbs/in.

Example II Six strips of the same piece of manila wrapping paper (7" x 1") were allowed to soak at a temperature of 75 C. for 1 hours in an HCl satu- The above experimental data indicate that thienyl tin compounds do not seriously afiect, but actually improve, the electrical properties of the halogenated organic compounds associated therewith and that, therefore, such compositions are eminently suitable for use in transformers, capacitors, switches, cables and other electrical devices.

The description of the present invention has been directed primarily to compositions containing thienyl tin compounds, chlorinated biphenyl and trichlorbenzene, but it is to be understood that the invention is not restricted thereto but embraces halogenated organic compounds'gen erally. Thus, the above compounds may be used as a scavenger or corrosion inhibitor for chlorinated naphthalene, chlorinated diphenyl ketone, chlorinated diphenyl oxide, chlorinated diphenyl methane, chlorinated diphenyl ethane, chlorinated benzene, chlorinated toluene, chlorinated nitro diphenyl, chlorinated alkylated benzenes, chlorinated alkylated biphenyls, ethyl trichlorbenzene, ethyl tetrachlorbenzene, ethyl penta'chl'orbenzene, chlorinated terphenyls, chlorinated quaterphenyls, chlorinated p'arafilnic hydrocarbons, chlorinated alicyclic hydrocarbons, chlorinated oxygen containing organic compounds, chlorinated rubber, chlorobutadiene polymers, chlorinated fats, chlorinated vegetable oils,'chlorinated animal oils, chlorinated mineral oils or mixtures of two or'more of these. In place of the chlorinated compounds, the corresponding fluorine, bromine and iodine derivatives may be used. In fact, any halogenated organic compound or composition which tends by reason of its halogen content to cause corrosion of metals or dehydration of paper or organic fibrous insulation, may be rendered substantially innocuous by means of thienyl tin compounds.

The method of incorporating thienyl tin compounds varies with the halogenated organic-compound or composition. If the compound or composition is liquid at room temperature, the above compound is merely dissolved therein in suitable concentrations; if it is a solid, the thienyl tin compounds are blended therewith by the use of solvents or swelling agents or by means of mixing rolls, etc. In the case of halogenated polymers, the "tin compound may be incorporated before, during or after polymerization of the corresponding monomers.

The quantity of thienyl tin compound used varies with the halogenated-organic compound or composition. In general, satisfactory results are obtained by employing this compound in an amount varying from 0.05% to 4% and preferably from 0.5% to 0.1% by weight of the halogenated organic compound or composition, but it is to be understood that the invention is not limited thereto as slightly lower and somewhat higher concentrations may be employed. Stated broadly, the above compound may be used in amounts varying from 0.01% by weight up to and above the limit of its solubility in the halogenated organic compound 'or composition. In most instances, it is desirable not to :exceed the solubility limits of the thienyl tin compound, but there are some applications such as heat exchanging operations in which this may be done without harmful effects.

As widely different embodiments of this invention may be made without departing from the spirit thereof, it is to be understood that the invention is not limited to the specific embodiments except as defined in the appended claims.

What I claim is:

1. A composition of matter consisting essentially of a halogenated aromatic compound and as :a scavenger therefor at least one of the group of compounds defined by the following general formula:

in which It represents an organic radical, at least one of which is a thienyl radical and the remaining ones are selected from the group consisting of aliphatic, :alicyclic and aryl hydrocarbon radicals, vcorresponds to the valence of tin and n is selected from the group of values consisting of 1 and '2 when u is 2 and 1, 2, 3 and l'when bis 4, said tin compound being employed in amount sufficient to render the decomposition products of said halogenated aromatic compound substantially innocuous.

2. A composition of matter consisting essentially of :a-chlor'inated aromatic compound and as a scavenger therefor at least one of the group of compounds defined by the following general formula:

in which R represents an organic radical, at least one of which is a thienyl radical and the remaining ones are selected from the group consisting of aliphati 'alicyclic and aryl hydrocarbon'radicals, 12 corresponds to the valence of tin and n is selected from the group of values consisting of 1 and 2 when 1; is 2 and 1, 2, 3 and 4 when dis 4, said tin compound being employed in amount varying from about 0.1% up to and above the limit of its solubility in said composition.

3. A heat transfer and dielectric composition consisting essentially of chlorinated biphenyl and as a scavenger therefor about 0.05% to about 4% by weight of an organic tin compound as defined in claim 1.

4. An insulating and cooling medium for electrical apparatus consisting essentially of a liquid chlorinated biphenyl and as a scavenger therefor about 0.05% to about 4% by weight of an organic tin compound as defined in claim 1, said chlorinated biphenyl containing from 42% to 60% by weight of chlorine.

5. A dielectric composition consisting essentially of chlorinated biphenyl and as a scavenger therefor about 0.05% to about 0.1% by weight of an organic tin compound as defined in claim 1, said chlorinated biphenyl containing from 42% to 60% by weight of chlorine.

6. The composition defined in claim 5 wherein tetra-a-thienyl tin .is the organic tin compound employed.

"7. The composition defined in claim 5 wherein di-a-tlilGllYl'tlIl'iS the organic tin compound employed.

8. The composition defined in claim 5 wherein triphenyl-a-thienyl tin is the organic tin compound employed.

9. A dielectric composition consisting of about 60% by weight of chlorinated biphenyl, about 40% by weight of trichlorbenzene and as a scavenger therefor about 0.05% to about 4% by weight of tetra-a-thienyl tin, said chlorinated biphen-ylcontaining about 60% by weight of chlo- -rine.

10. A dielectric composition consisting of about 60% by weight of chlorinated biphenyl, about 40% by weight of trichlorbenzene and as a scavenger therefor about 0.05% to about 4% by weight of di-a-thienyl tin, said chlorinated biphenyl containing about 60% by weightof chlomm.

11. An insulating and cooling composition for electrical apparatus consisting essentially of a liquid chlorinated biphenyl and as a scavenger therefor about 0.05% to about 0.1% by weight of tetra-a-thienyl tin.

12. An insulating and cooling composition for 9 electrical apparatus consisting of about 60% by Weight of chlorinated biphenyl, about 40% by weight of trichlorbenzene and as a scavenger therefor about 0.1% by weight of tetra-a-thienyl tin.

13. An electric arc quenching composition consisting of about 80% of chlorinated biphenyl, about 20% by weight of trichlorbenzene and as a scavenger therefor about 0.05% by weight of di-a-thienyl tin.

14. An electric arc quenching composition consisting of about 50% by weight of chlorinated biphenyl, about 50% by weight of trichlorbenzene and as a scavenger therefor about 0.1 by weight of tetra-a-thienyl tin.

15. A capacitor irnpregnant having substantially the following composition:

Per cent by weight Chlorinated b i p h e n yl containing from 42% to 60% by Weight of chlorine Chlorinated aromatic c 0 In p o u n (1 other than chlorinated biphenyl At least one of the group of compounds defined by the following general formula:

About 100-0 Per cent by weight in which R, represents an organic radical, at least one of which is a thienyl radical and the remaining ones are selected from the group consisting of aliphatic, alicyclic and aryl hydrocarbon radicals, 0 corresponds to the valence of tin and n is selected from the group of values consisting of 1 and 2 when u is 2 and 1, 2, 3 and 4 when 2) is 4 (101-4 16. A capacitor impregnant consisting of about 75% by Weight of chlorinated biphenyl (42%- 60% chlorine), about 25% by weight of trichlorbenzene and as a scavenger therefor about 0.1% by Weight of t1'iphenyl-a-thieny1 tin.

ARTHUR M. ELLENBURG.

REFERENCES SITE!) The following refer nces are or" record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,041,594 Clark May 19, 1936 2,440,100 Klabunde Apr. 20, 1948 2,468,544 Clark Apr. 26, 1949 

15. A CAPACITOR IMPREGNANT HAVING SUBSTANTIALLY THE FOLLOWING COMPOSITION: WEIGHT CHLORINATED B I P H E N Y L CONTAINING FROM 42% TO 60% BY WEIGHT OF CHLORINATED AROMATIC COMPOUND AT LEAST ONE OF THE GROUP OF COMPOUNDS DEFINED BY THE FOLLOWING GENERAL FORMULA: 